Acute effects of ischemic preconditioning and isometric exercise on blood pressure in prehypertensive males

This study investigates whether 5-min ischemic preconditioning (IR5) more effectively reduces submaximal exercise blood pressure and improves muscle oxygenation compared to 2-min ischemia (IR2) or 2-min isometric priming (IM2).

Twenty untrained men (10 prehypertensive; 10 normotensive) completed, in randomized order, IR5 (3 × 5 min bilateral limb occlusion at 220 mmHg), IR2 (3 × 2 min bilateral occlusion), and IM2 (3 × 2 min 30 % maximal voluntary contraction isometric knee extension), each followed by the submaximal exercise test. Outcomes were exercise heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), and vastus lateralis muscle oxygenation including Δdeoxyhemoglobin (ΔHHb), Δtotal hemoglobin (ΔtHb), and Δtissue saturation index (ΔTSI).

IR5 significantly attenuated the submaximal pressor response, reducing SBP by mean difference (MD) = -2.23 mmHg (P < .001, ηp² = 0.395) compared with both IR2 and IM2. A significant Condition × Group interaction (P = .023) indicated that the MAP reduction was confined to prehypertensive participants (MD = -3.14 mmHg, P = .003). During exercise, IR5 increased ΔtHb by MD = 1.56 μmol/L (ηp² = 0.606) and mitigated the decline in ΔTSI by MD = 2.98 % (ηp² = 0.716) without altering ΔHHb. In contrast, IR2 and IM2 elicited similar occlusion-phase deoxygenation but did not modify exercise hemodynamics or oxygenation metrics.

IR5 effectively lowers SBP and MAP during submaximal exercise and improves muscle oxygenation. It is a safe, non-pharmacological pre-exercise strategy to manage blood pressure and potentially reduce cardiovascular risk.